A recent study published in JAMA Network Open investigated the association between muscular strength and mortality in older women, controlling for aerobic activity, sedentary time, and fitness level. The analysis included 5,472 ambulatory women aged 63–99 years from the Objective Physical Activity and Cardiovascular Health in Older Women (OPACH) study, an ancillary study of the Women’s Health Initiative (WHI).
Study Methodology
Participants underwent in-home examinations measuring grip strength using dynamometry, timed chair stand performance, and usual-paced 2.5-m walk time as a proxy for cardiorespiratory fitness. Objective physical activity was measured via hip accelerometers over seven days. Mortality was tracked annually.
Covariates included demographics, comorbidities, health behaviors, body measurements, and estimated lean body mass. Serum high-sensitivity C-reactive protein (CRP) levels were assessed in a subset of participants to evaluate systemic inflammation.
Key Findings
The study observed that women with higher grip strength and faster chair stand performance had a lower risk of all-cause mortality during a mean follow-up of 8.3 years.
- A one standard deviation increase in grip strength was associated with a 12% reduction in mortality risk, even after adjusting for demographics, health status, and objectively measured activity.
- This inverse association between grip strength and mortality remained significant across various subgroups and was independent of whether women met aerobic activity guidelines.
- The association persisted after further adjustment for body weight, lean body mass, and inflammation markers (CRP levels), although it was slightly attenuated.
- Chair stand performance also showed an inverse association with mortality; however, this link was weaker and less consistently significant, especially in continuous models after full adjustment. Researchers noted that chair stand performance might reflect broader physiological aging and fatigability in addition to pure muscle strength.
Conclusion
The findings indicate that greater skeletal muscle strength, particularly grip strength, is associated with lower all-cause mortality in ambulatory women aged 63 to 99 years. This association was independent of other major risk factors and aerobic activity levels.
The study aligns with public health guidelines recommending regular muscle-strengthening activities for healthy aging. However, it's crucial to clarify that these results represent observational associations and do not prove that strength training directly extends longevity. Further research is suggested to determine optimal muscle-strengthening activities and to explore the mechanisms by which muscle strength impacts survival.